PHENACETIN

Drugs in Pregnancy and Lactation.

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Name: PHENACETIN
Class: Analgesic/Antipyretic
Risk Factor:    B

Fetal Risk Summary

Phenacetin, in combination products, is routinely used during pregnancy. It is metabolized mainly to acetaminophen (see also Acetaminophen).

The Collaborative Perinatal Project monitored 50,282 mother-child pairs, 5,546 of which had 1st trimester exposure to phenacetin (1, pp. 286–295). Although no evidence was found to suggest a relationship to large categories of major or minor malformations, possible associations were found with several individual defects (1, p. 471): Craniosynostosis (6 cases) Adrenal syndromes (5 cases) Anal atresia (7 cases) Accessory spleen (5 cases) The statistical significance of these associations is unknown and independent confirmation is required. Further, phenacetin is rarely used alone, being consumed usually in combination with aspirin and caffeine. For use anytime during pregnancy, 13,031 exposures were recorded (1, p. 434). With the same qualifications, possible associations with individual defects were found (1, p. 483): Musculoskeletal (6 cases) Hydronephrosis (8 cases) Adrenal anomalies (8 cases) In a surveillance study of Michigan Medicaid recipients involving 229,101 completed pregnancies conducted between 1985 and 1992, 368 newborns had been exposed to phenacetin during the 1st trimester (F. Rosa, personal communication, FDA, 1993). A total of 24 (6.5%) major birth defects were observed (16 expected), including (observed/expected) 6/4 cardiovascular defects, 1/1 polydactyly, and 2/1 hypospadias. No anomalies were observed in three other defect categories (oral clefts, spina bifida, and limb reduction defects) for which specific data were available. These data do not support an association between the drug and congenital defects.

Breast Feeding Summary

Phenacetin is excreted into breast milk, appearing along with its major metabolite, acetaminophen (2). A patient who consumed two tablets of Empirin Compound with Codeine No. 3 (aspirin-phenacetin-caffeine-codeine) produced an average phenacetin milk concentration of 71 ng/mL (2). Milk:plasma ratios in this and a second patient varied from 0.16 to 0.90 (2).

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References

  1. Heinonen OP, Slone D, Shapiro S. Birth Defects and Drugs in Pregnancy. Littleton, MA: Publishing Sciences Group, 1977.
  2. Findlay JWA, DeAngelis RL, Kearney MF, Welch RM, Findlay JM. Analgesic drugs in breast milk and plasma. Clin Pharmacol Ther 1981;29:625–33.

Index

Q&A about Phenacetin

jonathon
Why do we leave Phenacetin derivative for a week before the melting point is measured?
During recrystallization experiment, why do we leave Phenacetin derivative for a week before the melting point is measured?
gumbodum...
If you used water as a solvent, then your sample will still be wet once you filter it. Letting it dry over time will make sure you get the correct recrystallization MP, which isnt altered by water.
Phrozen
What is the stoichiometric reaction for the synthesis of phenacetin from acetaminophen (see image)?
http://img145.imagevenue.com/img.php?ima...

This is a Williamson Ether Synthesis.

See this image for the reaction.

Thanks!
pendarvi...
This is just a simple 2 reactants ---> 1 product reaction. Since you did not specify the quantities, 1 mole of acetominophen should give 1 mole of phenacetin. Usually this reaction is done with an excess of ethyl iodide to make it run a bit faster. Diethyl sulfate works somewhat better but that is extremely toxic.
e.danhoe...
What is the equation for the reaction to form phenacetin from p-phenetidine and acetic anhydride?
Schmedle...
C8H11NO + C4H6O3 --> C10H13NO2 + C2H4O2

C4H6O3 is acetic anhydride and C2H4O2 is acetic acid. The reaction places an amide group where the aromatic amine was in the starting material.
Miss
What are the name brands of OTC analgesics that contain phenacetin?
Windflow...
There shouldn't be ANY U.S. products that contain phenacetin! It is known to cause cancer and other problems. Here is some info:

Phenacetin was used as an analgesic and fever-reducing drug in both

human and veterinary medicine for many years. It was introduced into therapy in 1887 and was extensively used in analgesic mixtures until it was implicated in kidney disease (nephropathy) due to abuse of analgesics (Flower et al. 1985). Phenacetin was withdrawn from the

U.S. market in 1983 (Ronco and Flahault 1994, FDA 1998, 1999).

Carcinogenicity

Phenacetin is reasonably anticipated to be a human carcinogen based on sufficient evidence of carcinogenicity in experimental animals. When administered in the diet, phenacetin caused benign and malignant tumors of the urinary tract in mice and rats of both sexes and of the

nasal cavity in rats of both sexes (IARC 1982, 1987).

There is limited evidence for the carcinogenicity of phenacetin in humans because this medication was usually taken mixed with other drugs. Many case reports provide evidence that abuse of analgesic mixtures containing phenacetin results in kidney cancer (renal pelvic cancer) (IARC 1977, 1980).
kamaf
where can i get the infrared spectrum of phenacetin with peaks value?
plz i needed.

thank u in advance
Dr. C
Here is a link to the IR spectrum in the NIST Chemistry WebBook.

http://webbook.nist.gov/cgi/cbook.cgi?Sp...

If you want to know more, I suggest following their listed sources.
accomann...
why doesn't phenacetin or acetanilide dissolve in dilute hcl?
Chad
Neither is particularly polar and they do not have a functional group that can be protonated under those conditions (like an amide or pyridine).
LOL
explain why phenacetin is insoluble in base ?
Ajinkya N
If you have a look at the structure of phenacetin, you will see that it has almost no acidic hydrogens. So it is not soluble in base as salt formation is restricted.

Also the compound is almost a balanced dipole point. (Ethoxy and Amido groups are at para position)This causes a further decrease in solubility in polar solvents - including bases.
universi...
Which one of the following functional groups is in the structure of phenacetin (pain reliever)?
a)alcohol

b)amide

c)amine

d)ester

e)ketone
lady_ros...
The formula is C10H13NO2. If you want to see the structure go to www.chemfinder.com, write the name in the search box and see for yourself.

Just in case there is a ketone, amide, ether and a benzyl group...

Hope its useful...
kokguang...
why is phenacetin neutral?
Dr Dave P
Phenacetin is a acetanilinide (see ref) and acetanilides are slightly basic.

ref: http://en.wikipedia.org/wiki/Phenacetin
MARK T
is phenacetin a controlled drug in the uk?
Adrian F
Phenacetin was commonly used up to the 1980's but was found to be linked with cancers of the urological system and withrawn.

It is not now listed in the British National Formularly and as such can not normally be perscribed in the UK.

Paracetamol (known as acetaminophen in other countries) is a related chemical and is much safer.

The legal definition of a controlled drug in the UK is given in the Misuse of Drugs Act 1971. It limits the use of certain drugs, limits who can use them, how they can be stored and the way in which they are perscribed. Very drugs are controlled.